We've employed a texture analyzer to test mechanical keyboard switches. Here's what it can measure, and what it can't.
But before we dig into our testing methodology, it's more enlightening to start off by explaining what we don't do, and why.
How NOT To Test Switches
Some have tried to measure switch actuation and performance using tiny weights, and even in some cases, coins like nickels and dimes. This method is wholly inaccurate, for multiple reasons.
First, there is the issue of balance. Every key cap is shaped in a certain way, and maintaining the balance of multiple weights placed on top of them affects the measurement; it's far too easy for the weight to be off-center. Second, because the weight required to actuate a switch is so minute - often around 50g - the added force of placing (which amounts to dropping) even tiny <1g weights can throw off the measurement.
Some have tried to measure switch height (the distance to actuation, the switch travel and the depth of the rebound) with calipers. This can be somewhat accurate, but in our vetting process, we felt that, again, because of how tiny that distance is, human error made this method of testing too unreliable. Consider that the full path of a switch's travel is only a couple of millimeters; manually measuring to the tenth of a millimeter with any reliability is next to impossible.
In our own testing using a set of reasonably quality calipers, the results we collected were inconsistent. Further, testing is complicated by the inability of the tool to reach all of the keys, and without the ability to test more than a few on any given board, the results, even if they were accurate, would fail to provide sufficient data from which to draw any conclusions.
Why We Don't Test Key Caps
We know that many users are keen to test the durability of key caps - specifically, the printed characters. There are multiple ways of adding characters to key caps, and they each have their pros and cons. It makes some sense to perform abrasion testing to the key caps, and applying abrasion is simple enough. However, at this time, we have decided not to attempt abrasion testing. This is because although such testing would provide data, we're not convinced that it would offer relevant or actionable information. Besides, keycap wear is more likely to occur from dissolution (eg, the oils from your fingers) than abrasion.
Abrasion testing does not reproduce the normal, day-to-day wear and tear of fingers on a keyboard, and it offers no sense of longevity. For example, if the printing on one key cap lasts for 10 minutes under duress before fading, and another lasts for 12 minutes under the same conditions, you come away knowing that one lasts longer than the other, but nothing about how long the printing will last in real life. Maybe the former would hold up for five years, and the latter for five years and six months. One is "better" than the other, but it's possible that the "worse" of the two is actually more than sufficiently durable. Therefore, that data is not useful to you, the reader, prior to your purchase.
Longevity Simply Takes Too Long
One aspect of switch testing that would be of benefit to readers is confirming (or debunking) common switch maker claims of switch longevity. Typically, switches are rated for tens of millions of keypresses. Testing these claims is beyond the scope of normal reviews, though. Even with a proper fatigue testing machine, it would take months to reach, say, 50 million clicks on a single keyboard's worth of switches. (For reference, there are approximately only 31 million seconds in one year.)
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